Earth Science, Geology, Physics. Take a look at a globe or a map of the world and you may be impressed by what you see. Towering mountains, deep oceans, vast continents, and sprawling glaciers—they make Earth what it earth today. Scientists have calculated the age of our planet to be approximately 4. But how did scientists determine that age? The answer is complicated: It involves everything from observation to complicated mathematics to understanding the elements that make up our planet. In the s, as scientists sought to determine the age of the planet, they made a few missteps.
Ina famous Earth physicist and mathematician, Lord Kelvin, estimated that Earth was between million and million years old. While that is an enormous span of time, even an age of million years would make the planet quite young in relation to the rest of the universe.
Lord Kelvin based his conclusion on a calculation of how long it would have taken Earth to cool if earth had begun as a molten mass. While his estimate was wrong by a significant margin, his technique of drawing conclusions based on observations and calculations was an accurate scientific method. Scientists also tried to use relative dating techniques to determine the age of the planet. Stratigraphy compares the configuration of layers of rock or sediment in dating to determine how old each layer is in relation to one another.
This technique can reveal which layers are older or which events happened before others if the layers of sediment have remained in sequential order. Layers can be rearranged, bent, or contain inconsistencies. However, stratigraphy yields no exact age for those layers or events. Nonetheless, even though this technique did not give scientists the precise number they were looking for, it did suggest that Earth was most likely billions of years old, and not just millions as was previously thought. As advances in chemistry, geology, and physics continued, scientists found a method by which the absolute age—an actual number of years—of a rock or mineral sample could be determined.
This method is called radiometric datingand it involves the decay, or breakdown, of radioactive elements. Using radiometric dating techniques, it became possible to determine the actual age of a sample.
Radiometric dating requires an understanding of earth. Isotopes are variations of an element differentiated by the number of neutrons in their nuclei. The isotopes of unstable radioactive elements—known as parent isotopes—eventually decay into other, more stable elements—known as daughter isotopes—in a predictable manner, and in a precise amount of time called a half-life.
The half-life of an element is the amount of time required for exactly half of a quantity of that element to decay. The age of a sample can be determined based on the ratio of parent to daughter isotopes within the sample.
Dating Methods
One earth with this approach to dating rocks and minerals on Earth is the presence of the rock cycle. During the rock cycle, rocks are constantly changing between forms, going back and forth from igneous to metamorphic to sedimentary.
This earth finding an exact age for Earth difficult, because the original rocks that formed on the planet at the earliest stages of its creation are no longer here. The oldest rocks that have been found dating mature sites gay dating 3. To get around the difficulty presented by the rock cycle, scientists have looked elsewhere in the solar system for even older rock samples.
They have examined rocks from the moon and from meteoritesneither of which have been altered by the rock cycle.
References and Recommended Reading
The same techniques of radiometric dating have been used on those rocks. All the data from Earth and beyond has led to the estimated age of 4. The audio, illustrations, photos, and dating are credited beneath the media asset, except please click for source promotional images, which generally link to another page that contains the media credit.
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Development of modern geologic concepts
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